How Much House Can You Really Afford?

§ 01 — TWO DIFFERENT QUESTIONS Why Banks and Buyers Are Solving Different Problems

When a lender pre-approves you for $500,000, they're answering a specific question: based on the data they have, what's the largest loan amount where their statistical models still show acceptable default risk? The answer reflects what they're willing to lend, not what you should comfortably borrow.

Their math typically allows a debt-to-income ratio (DTI) up to 43% — meaning total debt payments including the mortgage can consume 43% of your gross income. Some loan programs go higher, up to 50%. These ceilings come from regulatory requirements and the bank's risk tolerance. They are not financial planning advice.

The financial-planning answer is much more conservative: total housing costs should stay at or below 28% of gross income, and total debt payments at or below 36%. These are the famous 28/36 ratios that responsible lenders followed for decades before the deregulation cycles of the 1990s and 2000s.

The gap between 28/36 and 43% is enormous. On a $120,000 income, the difference between these two limits represents about $1,400/month — the difference between a comfortable life with savings and a stressful life one job loss away from disaster.

§ 02 — THE 28/36 RULE The 28/36 Rule, Explained Properly

The rule has two parts that work together:

28% — the front-end ratio. Your total monthly housing payment (principal, interest, property taxes, homeowners insurance, HOA fees, and PMI if applicable) should be no more than 28% of your gross monthly income. On a $10,000/month gross income, that's $2,800 maximum housing cost.

36% — the back-end ratio. Your total monthly debt payments (the housing payment plus all other debt: car loans, student loans, minimum credit card payments, alimony) should be no more than 36% of gross income. On the same $10,000/month, that's $3,600 maximum total debt service.

Both have to be satisfied. If you have $400/month in other debt payments, your housing budget is the lesser of $2,800 (from the 28% rule) and $3,200 ($3,600 minus the existing $400 in other debt). The binding constraint is whichever is smaller.

Why these specific numbers? Because below them, most households have enough breathing room to save aggressively, absorb financial surprises, and make financial decisions out of want rather than necessity. Above them, financial life narrows: every car repair becomes a credit card emergency, every vacation comes from somewhere it shouldn't, and savings rates drop to numbers that endanger long-term goals.

§ 03 — REAL NUMBERS What You Can Afford on $100,000 of Income

Take a household earning $100,000 gross per year (about $8,333/month), with $400/month in existing debt payments, putting 20% down at a 6.5% mortgage rate.

That's a $134,000 difference in price for the same income — and an $850/month difference in payment. The 28/36 number is what you should treat as your real budget. The bank's number is what you should treat as a warning label.

§ 04 — HIDDEN COSTS What 28% Doesn't Include (And You Should)

Even hitting the 28% target doesn't capture everything you'll spend on the house. Four costs people consistently underestimate:

• Maintenance and repairs. Budget 1-2% of home value annually. On a $400,000 house, that's $4,000-$8,000/year, or $330-$670/month. Some years you'll spend nothing; others, a roof replacement will obliterate the average. Set aside the average regardless.
• Furniture and setup. First-time buyers routinely spend $5,000-$25,000 setting up a new home in the first year. Window treatments, mattresses, lawn equipment, washer/dryer, the small things that add up to large numbers fast.
• Utility increases. Larger homes cost more to heat, cool, and light. The transition from apartment to house often doubles utility bills.
• Property tax growth. In many jurisdictions, property taxes can rise faster than your income. A 4% annual increase on a $5,000 tax bill adds $200/year, indefinitely.

The cleanest way to handle this: budget at 25% of gross income for housing instead of the 28% maximum, and use the saved 3% as a buffer for these inevitable extras.

§ 05 — DOWN PAYMENT REALITY Does 20% Down Still Matter?

The conventional wisdom — always put 20% down — is more nuanced than the slogans suggest. The original reason for 20% was simple: it eliminates Private Mortgage Insurance (PMI), which adds 0.5-1.5% of the loan amount per year for nothing in exchange.

But waiting years to save 20% has costs the slogan ignores. Home prices and rents tend to rise faster than savings accounts. Mortgage rates fluctuate, sometimes punishing patience. The math of "wait three years to save 20% and avoid PMI" frequently loses to "buy now with 10% down, pay PMI for two years until equity hits 20%, refinance to drop PMI."

The honest framework:

• If you can save 20% within 18-24 months, wait. The PMI savings will likely exceed the home appreciation you miss out on.
• If reaching 20% would take 4+ years, don't wait. Buy with 5-10% down, accept the PMI temporarily, refinance when equity catches up.
• Don't drain your emergency fund to hit 20%. A homeowner without liquid savings is one HVAC failure away from carrying credit card debt at 22% APR — vastly worse than PMI at 1%.

§ 06 — STRATEGIC UNDERBUYING The Underrated Strategy: Buy Below Your Max

Buying a house at 20-22% of gross income — well below the 28% max — sounds like leaving money on the table. It's actually the move that most quietly builds wealth.

The math: a household making $120,000 with a 20% housing budget has $24,000/year going to housing. The same household at 28% spends $33,600/year. That $9,600 difference, invested in retirement accounts at 7% real returns over 30 years, becomes roughly $970,000.

This isn't theoretical. Studies of high-net-worth households consistently find that they live in smaller, less expensive homes than their incomes would justify. Wealthy people generally don't max out their housing approval letter. They buy what they comfortably need, then invest the difference.

The psychological trap is that home size is socially visible while investment account balances are not. A bigger house demonstrates apparent prosperity in ways your retirement balance can't. The actual wealth, however, is sitting quietly in the account that no one sees.

§ 07 — BOTTOM LINE The Bottom Line

The bank will tell you what they're willing to lend. That number is not your budget. It's the upper limit before their statistical models start flagging you as risky — which is much higher than the limit at which your life starts feeling tight.

Use 28% of gross income as your firm housing-cost ceiling, and ideally aim for 22-25% to leave room for the costs that don't show up in mortgage calculators. Verify the back-end ratio (36% total debt) is also satisfied. Add up maintenance, furniture, and utility increases honestly before committing.

The house you stretch to afford will limit every other financial decision you make for the next 15-30 years. The house you can comfortably afford gives you the breathing room to actually build wealth while living in it.